These steps are for CoolFocus 5.
Clients booking online can only pick a time where you have an opening. If it's on your calendar as an open time, she can book it. If it isn't, she can't.
This is true for your booking page, the widget, partner apps and the Scheduler API. Staff are different: you can book a client at any time inside your hours.
What clients can book
A time shows online when all of these are true:
There's an opening for that appointment type, at that location.
It starts inside the location's hours, and isn't under closed time.
The appointment type is turned on for online booking.
It isn't too soon or too far ahead (the notice and how-far-ahead you set on the type).
Two openings at 9:00 show as one 9:00, and clients can choose it until both are taken. A booking page or widget lists only the types and locations that have an opening coming up.
Turn a type on or off
Go to Settings → Scheduler → Appointment Types and open the type.
Open the Online tab.
Switch Online booking on or off. Here you also set Minimum notice (hours), How far ahead (days), Clients can reschedule, and Partner integrations.
That tab is the only place to turn a type on or off. Settings → Client Portal → Online Booking shows On or Off for each type, with a link to this tab.
When a client books
The booking takes its opening, so one opening is one client, whether staff or an online client got there first. If the appointment is cancelled, the opening comes back.
To offer fewer or more times
Delete an opening, or close the time with a block, to stop offering it. Add openings to offer more. See Openings on Your Calendar.
If a client says she can't find a time, see Why Can't I Book This?.